BEIRUT (AP) — Opposition activists say shelling and airstrikes on the last major rebel-held stronghold in northwestern Syria has killed at least three people.

The opposition Syrian Civil Defense, also known as White Helmets, says an airstrike on the town of Khan Sheikhoun killed three children and wounded eight on Tuesday.

The Britain-based Syrian Observatory for Human Rights, a war monitoring group, gave a higher toll, saying five people were killed — three children in an airstrike and two women in artillery shelling.

Khan Sheikhoun is located in Idlib province, which is the last major rebel stronghold in Syria.

Violence has intensified over the past weeks there after al-Qaida-linked militants captured much of the province.

The violence has been ongoing despite a truce in the area reached in September between Russia and Turkey.